Parrotfish (family Scaridae)

In one of my classes we were talking about sleep in animals, and of course we quickly started talking about aquatic animals. After all, you don’t usually think about fish sleeping. They’d sink, wouldn’t they? Well, I’m not really well versed on sleeping in marine organisms, but an interesting fact came up about parrotfish, and of course I immediately thought about blogging. So today’s post is all about these funky fish.

Parrotfish are a family of fishes that live in tropical oceans around the world. They usually hang out in coral reefs, where their colourfulness adds to the lovely atmosphere of the place. Of course, they’re also a leading cause of bioerosion in coral reefs, which is not as good for tourism.

The parrotfish is so named because of its teeth. These are arranged very close together, so that they form a beak (which I’m sure you can guess resembles a parrot’s). These teeth are adapted to the parrotfish’s diet, which consists mainly of coral and algae. The fish takes bites out of coral and uses its teeth to grind up the tough coral to get to the tasty nutritious parts inside. This of course leaves a lot of gritty indigestible parts, which the parrotfish excretes as sand. A single fish can create 90 kg of sand every year. Which is a fairly large chunk of sand, if you ask me. Schools of parrotfish can produce enough sand to help create small islands, and beautiful sandy beaches. So next time you’re on a Caribbean cruise and admiring the sparkling white sand, just remember you’re probably walking on some sand that’s been through a fish. Pretty cool, right?

There are around ninety species of parrotfish, and many of them have different ways of reproduction. One common theme, however, is the ability of parrotfish to change gender. In many species, fish are born female, and as they age they change to males (these are brightly coloured, the females being plain reddish brown or grey). Some parrotfish form harems, with one male protecting a number of females and guarding them vigorously. If this male dies, one of his females will change into a male and become the new harem master. Which doesn’t seem very loyal, but I guess fish aren’t as a general rule.

So back to fish sleep. You can imagine that sleeping in the ocean wouldn’t be very safe. So some species of parrotfish have a solution for this – they secrete a mucus cocoon that envelops their body. It’s thought that this helps hide their scent from predators, as well as serving as an early detection system in the event of a predator attack. And who knows, maybe it makes the fish feel warm and safe, like when you wrap yourself in a giant duvet. I hope so, for the parrotfish’s sake.

There are definitely some strange things in the ocean. I keep wondering which fish I’ll blog about next, and worrying that they won’t be strange enough. So far that doesn’t seem to be a problem!

Cover image By Leonard Low from Australia – Flickr, CC BY 2.0